Human limb flexibility, including muscle extensibility and joint mobility is known to be of importance in the prior art in sport and general fitness for the avoidance of injury and improvement of performance as well as in clinical rehabilitation following injury.
The hip joint is of considerable importance regarding athletic activity. Abnormal function of the hip pre-disposes the subject to a variety of sports injuries. In the non-athletic population hip dysfunction may ultimately lead to arthritis and back pain. Stretching exercises are known to be used to improve hip mobility to reduce predisposition to injury or disorder. Hip stretching exercises are difficult to perform unaided, that is in the absence of a physiotherapist, due to the need to stabilize the pelvis, thus isolating the hip joint to ensure that movement takes place only at/around the hip joint whilst conducting the exercises and also due to the considerable forces required to overcome tightness in strong muscles and other soft tissues of the hip joint in performing the stretches.
A small number of prior art stretching apparatus are known including U.S. Pat. Nos. 4,574,789, 5,405,306, 4,647,040, FR 2613238, U.S. Pat. Nos. 5,449,336, 5,261,865, 4,819,936 and FR 2,357,236.
U.S. Pat. Nos. 5,405,306, 5,449,336 and 5,261,865 all disclose stretching apparatus for stretching of human lower limbs. Each apparatus consists of a frame provided to allow a subject to be positioned in a supine position, that is on their back. A material loop or cuff is provided for positioning over the foot or ankle of the subject wherein the cuff is connected to a cable. The cable is arranged over a system of pulleys to extend to a handle connected to one end of the cable. By pulling on the handle the subject can raise and lower one or both legs to perform a stretch. In U.S. Pat. No. 5,405,306 the cable can be arranged through one of a plurality of pulley sets to enable both flexion and abduction stretches of the lower limbs. In U.S. Pat. Nos. 5,449,336 and 5,261,865 a belt is provided to encircle the subject's waist in order to stabilize the pelvis against the base platform of the apparatus.
Prior art apparatus of a type such as that disclosed in U.S. Pat. No. 5,405,306 requires substantial variation of the setup configuration to perform more than one type of stretch. Limited abduction and adduction of the hip joint can be performed by pulling of cables to transfer a component of force to the coronal plane. This system is energy inefficient and introduces unwanted force components which act to stretch the limb in other planes of movement and which result in undesirable strain of the stretching muscles. The result is a mixing of stretches which limits the ability to controllably perform a desired stretch.
FR 2613238 and U.S. Pat. No. 4,647,040 provide stretching apparatus arranged for abduction of the lower limbs. Leg supports are provided upon which the subject rests their legs. An actuating arm enables the subject to perform abduction stretches.
U.S. Pat. No. 5,913,759 discloses apparatus for performing extension stretching of the thigh muscles wherein an arm member contacts the front muscles of the users thigh and a motor is provided to urge the arm contacting the thigh downwardly thus stretching the thigh muscles on the front side of the leg.
FR 2357236 discloses apparatus for performing kinetic joint therapy wherein a moving panel hinges on a horizontal fixed panel. The moving panel provides a leg support and the fixed panel may be used to secure the upper body in position. This apparatus relies on the leg muscles of a subject or a second person to position the moving panels; it has no actuating means by which the subject can effect movement. Furthermore, it does not allow adduction or rotation stretches to be performed.
Prior art stretching apparatus provides for specific lower limb stretching exercises to be performed. The use of cable and pulley systems is disadvantageous for several reasons. Use of cable and pulley systems does not enable precise movement of the limb during stretch as the cable is flexible to pivot about the pulleys such that the limb being stretched cannot be maintained within a single desired plane of stretch. Further, where the subject is required to manually operate the application of tension to the cables by pulling on the cable ends the tension applied to the stretch cannot be maintained uniform. This also results in the fatigue of the subject through application of tension to the cables which results in inability to maintain the limb in the stretched position.
When considering hip stretching exercises no single prior art apparatus provides for controlled stretching of the hip joint in all six anatomical directions. Where cable systems are used the prior art apparatus are required to be adjusted by repositioning or reattachment of the cable pulley system between different stretches. Use of straps or cuffs attached to the ankles results in uncontrolled stretching and use of the cable system has a result that the lower limb being stretched is subject to undesirable compressive or tensile forces along its length.
In order to perform controlled stretching of single lower limbs it is necessary to position the resting lower limb in a substantially fixed resting position. The prior art apparatus does not provide means for positioning the resting limb in a predetermined resting position which assists stretching of the stretching limb.
It is also known in the prior art that during flexion stretching the thigh of the resting leg will tend to rise as the stretching leg reaches maximum tension. This is unwanted as the subject's pelvis is tilted backwards as a result which reduces the effectiveness of the stretch.
Isokinetic testing apparatus, such as the Multi-Joint System 3 apparatus manufactured by Biodex Medical Systems Inc. New York, USA are also known in the prior art. Such isokinetic testing apparatus provide means for measuring muscle strength by application of a resistive force to a limb against which the subject pushes. These machines are known in the prior art for use in monitoring muscle strength and are useful in monitoring a subject's recovery from injury. In the prior art, apparatus for improving and/or monitoring muscle strength do not provide for stretching of the same muscles in a controlled manner.